Definition
Arterial hypertension is a long-term condition where blood pressure in the arteries is persistently elevated above 140/90 mmHg. It can lead to serious complications like coronary artery disease, stroke, heart failure, peripheral vascular disease, and vision loss.
Blood pressure depends on:
- Cardiac output (CO) × Peripheral resistance (PR).
Classification
- Primary hypertension (essential hypertension): no clear cause, most common type (about 95%).
- Secondary hypertension: caused by an identifiable disease or condition, less common (about 5%).
Primary Hypertension
Etiology (Causes)
- Family predisposition.
- Atherosclerosis.
- Hyperlipidemia (can be essential or secondary to diabetes, hypothyroidism).
- Obesity and lack of exercise.
- High salt intake.
- Stress, smoking, excess alcohol consumption.
- Hyperactivity of the sympathetic nervous system (SNS).
- High renin levels, causing sodium and water retention: ↑ Renin → ↑ Angiotensin II → ↑ vasoconstriction, thirst, ADH and aldosterone → ↑ Na⁺ reabsorption → ↑ blood volume → ↑ BP.
- Old age (vessels stiffen over time).
Pathophysiology
- Arterial pressure is determined by cardiac output (CO) and peripheral resistance (PR).
- CO depends on stroke volume (SV) × heart rate (HR).
- Stroke volume relates to heart contractility and vascular compartment size.
- Peripheral resistance comes from functional and anatomical changes in small arteries and arterioles.
Disease course:
- Early: ↑ CO, normal TPR.
- Later: Normal CO, ↑ TPR.
Theories explaining hypertension:
- Overactive RAAS → vasoconstriction + water retention → high BP.
- Overactive SNS → increased stress response.
- Polygenic factors → multiple gene involvement.